NMR EVIDENCE FOR COMMON MAGNETIC-BEHAVIOR IN YBA2CU4O8 AND YBA2CU3O7-DELTA

High resolution Y-89 NMR measurements in YBa2Cu4O8 (Y124) have shown that the shift has the same value and same temperature dependence as that of YBa2Cu3O7-delta with the same T(c) (delta = 0.2). This indicates that T(c) and the Y-89 shift are strongly correlated and suggests that T(c) is closely related to the susceptibility in the Cu-O planes. The normal state NMR data provide further evidence in favour of the one-component model in which only a single uniform spin susceptibility needs to be considered in a unit cell of the Cu-O planes in Y-Ba-Cu-O system. The ratio of 63Cu perpendicular-to (2) to Y-89 shifts is found to be -11.5 +/- 0.6 for Y124 which is to within the experimental error the same as those for the 90 K and 60 K 123 phases, indicating a constant ratio of the 63Cu perpendicular-to (2) to Y-89 hyperfine coupling in the Y-Ba-Cu-O system.